Bridge Vocabulary & Questions

Pile

a long, round pole of wood, concrete, or steel driven into the soil by pile drivers

Compression

a pressing force that squeezes a material together

Cantilever

a projecting structure supported only at one end, like a shelf bracket or a diving board

Truss

a rigid frame composed of short, straight pieces joined to form a series of triangles or other stable shapes

Beam

a rigid, usually horizontal, structural element

Anchorage

a secure fixing, usually made of reinforced concrete to which the cables are fastened

Beam Bridge

a simple type of bridge, composed of horizontal beams supported by vertical posts

Tension

a stretching force that pulls on a material

Cable

a structural element formed from steel wire bound in strands; the suspending element in a bridge; the supporting element in some dome roofs

Pier

a vertical supporting structure, such as a pillar

Continuous bridge beam span

simple bridge made by linking one beam bridge to another; some of the longest bridges in the world are ...

Deck

supported roadway on a bridge

Span

the distance a bridge extends between two supports; (v.) to traverse a specific distance

Abutment

the outermost end supports on a bridge, which carry the load from the deck

Bedrock

the solid rock layer beneath sand or silt

Tower

the vertical structure in a suspension bridge or cable-stayed bridge from which cables are hung; also used loosely as a synonym for the term skyscraper

Load

weight distribution throughout a structure; loads caused by wind, earthquakes, and gravity, for example, affect how weight is distributed throughout a structure

Aqueduct

a bridge or channel for conveying water, usually over long distances

Cantilever, third, central

A complicated version of a truss bridge is called a _________________ bridge. In this type of bridge there is normally a ___________, ___________ span.

Shear force

A force that causes parts of a material to slide past one another in opposite directions

Girder

A large horizontal support beam

Aluminum

A lightweight chemical element (AL); the most abundant metallic element in the Earth's crust

Plastic

A synthetic material made from long chains of molecules; has the capability of being molded or shaped, usually by the application of heat or pressure.

Steel

An alloy (mixture) of iron and carbon that is hard, strong, and malleable

Eiffel Tower and the bridge in Garabit Valley (Garabit Viaduct)

Gustav Eiffel created...

Heavy concrete pillars, or piles , are used. They rest deep in the earth on stable, solid ground.

How can a bridge be strengthened in soft soil?

Roller joints can be used. They give beams and columns the freedom to expand or contract when the temperature changes.

How can a bridge be strengthened to combat thermal load?

A thicker beam can be used. The thicker the beam, the less likely it is to bend. Used in structures with live or dynamic loads.

How can a bridge be strengthened to combat vibration?

Diagonal braces, usually made of steel, are used to strengthen and stabilize all kinds of structures.

How can a bridge be strengthened to combat wind?

Use a diagonal brace.

How do you strengthen a rectangle or square? (look in packet for diagram of forces)

When you poke the top of the triangle, the two sides squeeze together and the bottom side pulls apart. The triangle doesn't bend because each side experiences only one force at a time. When used properly, triangles are the most stable and rigid shapes used in construction today.

How do you strengthen a triangle? (look in packet for diagram of forces)

Use buttresses, which push back on the sides of the arch and prevent it from spreading apart.

How do you strengthen an arch? (look in packet for diagram of forces)

The Industrial Revolution

In 1770 Smelting coal helped create cast iron. Pieces could be molded in sand from molten metal. Machinery, tools, and bridge pieces could be fabricated and assembled later. This is the beginning of what monumental time period?

Weak in resisting tension and could not resist the forces of heavy iron locomotives

Iron Bridges failed why?

Dynamic Loads

Loads that change over time, from wind gusts to pounding objects.

Beautiful to view

"Aesthetics" refers to what?

Cast Iron

A brittle alloy with high carbon content; iron that has been melted then poured into a form and cooled; can be made into any shape desired

Wood

A common natural material strong in both compression and tension

Dynamite

A blasting explosive, based on nitroglycerin, but much safer to handle than nitroglycerin alone

Balanced forces

Bridges stay up because there are...

It gives a beam bridge the ability to span over great distances (250 feet +). The Chesapeake Bay Bridge tunnel is an example.

Describe a continuous span bridge; include one example.

Beam, arch, continuous span, suspension bridge

Put the bridges in order of typical span length, from shortest to longest. Do not include a truss bridge in this list.

Shear When parts of a material slide past one another in opposite direction (earthquakes)

Sliding causes a force called _____________________. What causes sliding?

Structural Engineer

Someone who studies bridges and buildings to make sure they are safe is a

Compression Columns

Squeezing causes a force called _________________ What tends to be "squeezed" in a bridge?

Tension Cables

Stretching causes a force called ____________________. What tends to be "stretched" in a bridge?

England

The first iron bridge was built in what country?

Golden Gate Bridge

The huge suspension bridge in San Francisco is the...

Torsion Wind

Twisting causes a force called _____________________ What causes twisting?

Live Load

Weight of objects on the structure is called the __________________________

Dead load

Weight of structure is called the ________________________

Pro- They are strong, and long lasting Con- Expensive, hard to work with, and heavy

What are pros and cons of stone bridges?

The air pressure, pumped into the caisson needs to increase as water depth increases. This causes bubbles of n2 in the blood, if one comes out to the surface too fast, their joints will be very painful. This condition is known as "bending"

What are some dangers associated with the structure mentioned in the previous question?

Cable Stayed Bridge require less cable, and can be built faster.

What are the benefits of a cable stayed bridge?

Brooklyn Bridge, suspension bridge

What bridge connects Manhattan and Brooklyn and what type is it?

Arch bridges

What bridges did the Romans build?

Tension (top) and Compression (bottom)

What causes bending?

Winds or pounding objects cause vibrations that can become bigger and more dangerous over time.

What causes vibration in a bridge?

International orange

What color is the bridge in the previous question?

Bridge builder in Latin

What does "pontifex" mean?

It causes the beams and columns to change shape and push and pull on other parts of the structure.

What does temperature do to a bridge?

Caisson

What is the air filled chamber called that is used to burrow below river bottom so that towers of a suspension bridge can sit on solid ground?

Keystone

What is the stone at the top of an arch called?

Steel

What material is best under compression (takes the longest to crack when squeezed)?

Steel

What material is best under tension (takes the longest to crack when stretched)?

Brick, wood, and concrete

What material is the least expensive?

Plastic and aluminum

What material is the most expensive?

Wood

What material weighs the least?

Steel

What material weighs the most?

Thermal Load

When a structure expands or shrinks with the temperature.

Earthquake load

When the ground beneath a structure jerks back and forth during an earthquake.

Wind load

When wind blows on a structure. They push horizontally.

With more cars, people could live farther from the city. Ferry traffic took too long. Needed to reach the rich natural resource northern areas more easily if economy was to grow

Why did the bridge in need to be built?

The weight pushes down on the piers, weakening them. The farther apart the the piers, the weaker the bridge.

Why do beam bridges rarely span more than 250 ft?

It is unstable until the keystone is placed in the middle.

Why is building an arch bridge not easy?

Cable stayed bridge

a bridge in which the roadway deck is suspended from cables anchored to one or more towers

Suspension Bridge

a bridge in which the roadway deck is suspended from cables that pass over two towers; the cables are anchored in housings at either end of the bridge

Torsion

an action that twists a material

Civil Engineer

an engineer who plans, designs, and supervises the construction of facilities essential to modern life